A huge 'EVET = Yes' poster by the Justice and Development Party of Prime Minister Recep Tayyip Erdogan is seen near the Galata Bridge in Istanbul, Turkey, Friday, two days ahead of a referendum on changes to the constitution that was crafted in the wake of Turkey's 1980 military coup.

Istanbul, Turkey — Turks are preparing to vote on a package of far-reaching constitutional changes Sunday, in what has turned into a referendum on the country’s Islamic-leaning ruling party.

Critics say the Justice and Development Party (AKP) is bent on an Islamist agenda, and wants to erase modern Turkey’s secular traditions, further weaken once-hallowed state institutions like the military, and manipulate the judiciary to increase its own power.

Prime Minister Recep Tayyip Erdogan and his ministers have argued that their sole aim is to liberalize the 1982 constitution, imposed after a military coup, by democratizing the state in line with European standards, while better protecting the rights of every citizen.

Mr. Erdogan called the vote the “most important” event in Turkey’s recent political history. But despite eight years in power – during which Turkey became the world's 15th-largest economy – the AKP has not been able to bridge the social, political, and economic divisions enough to stave off public mistrust of its intentions.

Polls suggest the amendments will pass, though by a small margin – a result that analysts say would likely entrench current problems.

“A slim majority will not be sufficient to put an end to the debates, if anything it will inflame the debate further and will show just how divided the country is,” says Semih Idiz, a columnist for the Milliyet newspaper. “If it’s in the middle somewhere… people might say we’ve just replaced a military constitution with an AKP constitution.”

The vote has “turned into an indication of the government’s lack of support or not; it’s got nothing to do with the Constitution at this stage,” says Mr. Idiz

26 amendments

On many of the 26 amendments, there is little controversy.

In line with European Union requirements – Turkey has for decades aimed to become a member of the European club – there are special protections for children, women, and other vulnerable citizens, and improvements in civil society such as greater ability for workers to strike.

But other points have drawn more criticism, such as changes that would grant more power to elected officials to shape key judicial bodies that have long been conservative bastions, such as the Constitutional Court and High Council for Judges and Public Prosecutors.

“Some of the changes – like changing the [makeup] of the judiciary – make some believe that what the government is doing here is securing its own future, because there are key elements of democracy that are not there,” says Idiz, criticizing the "veneer of democracy" presented by the AKP. “If you are going all out for democracy, then one would assume the first thing you would do would is guarantee the freedom of expression, and that is certainly not the case."

AKP did not seek broad consensus

Much of the resentment over the proposed package of constitutional reforms, however, is more about process than content: they were presented as a fait accompli by the AKP, analysts say, with little input from rival parties.

“The problem is not the actual constitutional amendments, but rather the political culture in Turkey surrounding all the amendments,” says Fadi Hakura, a Turkey expert at the Chatham House think tank in London. “[The ruling party] has taken advantage of its majority presence in Parliament, as well as control of the executive and the municipalities, to really push through these amendments without the broad consensus that is needed for such an important document."

That was not always how the AKP did things. Between 2002 and 2004, notes Mr. Hakura, Turkey passed nine major constitutional packages in cooperation with the opposition Republican People’s Party, which is now advocating a 'no' vote on Sunday.

But Erdogan, who has put his prestige – and a possible third term – on the line, rejects opponents' claims that the AKP is acting unilaterally.

“At the moment there is a flood of disinformation and black propaganda that claims these reforms are my personal project, or a project of my party,” Erdogan said in an interview with the BBC. “These claims are unfounded.”

Why it's become a grudge match

The AKP has for years been locked in legal battles over its status as a party with an Islamic foundation. Prosecutors tried to shut down the party in 2002, and again in 2008, for its religious leanings – a fate that befell its more overtly Islamist predecessors.

But changes to the Constitution are not new. One Turkish think tank estimates that one-third of the 1982 document has already been reconstructed to increase civilian rule and democratic rights.

“This isn’t a military constitution as such; there’s been countless amendments since 1982 – the death penalty was abolished, for one, and there were many changes made for the sake of the EU perspective, so it’s not as if we have a military constitution in hand that hasn’t been changed,” says Idiz of Milliyet.

Still, the issue has turned into a political grudge match between the AKP and its many enemies, which will play out on Sept. 12 – coincidentally the 30th anniversary of the 1980 military coup, one many such interventions carried out by the armed forces to preserve the secular nature of the state since its founding in 1923 by Mustafa Kemal Ataturk.

Besides the Constitution, there remain the bitter memories of that undemocratic action. Military coup leaders shut down Parliament for three years, suspended the Constitution, and imprisoned civilian officials.

More than half a million people were detained and 230,000 people prosecuted in military courts – 14,000 of them stripped of their citizenship. Official figures say 300 people died, 171 of them under torture.